1. Field of the Invention
This disclosure relates to a liquid crystal display device and a manufacturing method thereof.
2. Discussion of the Related Art
The importance of a flat panel display (FPD) has been emphasized following the development of multimedia technologies. In response to this trend, various flat type displays such as a liquid crystal display, a plasma display panel, and an organic field emission display have been put to practical use. Among them, some display devices, e.g., liquid crystal display devices and organic field emission displays, have devices and wires formed in a thin film shape on a substrate by deposition, etching, and so on.
The driving principle of liquid crystal display devices utilizes optical anisotropy and polarization properties of liquid crystal. Liquid crystal has directionality in the alignment its molecules due to its slender and long structure. Hence, it is possible to control the orientation of the liquid crystal molecules by artificially applying an electric field to the liquid crystal. Accordingly, by arbitrarily controlling the arrangement direction of the liquid crystal molecules, the alignment of the liquid crystal molecules is changed, so that an incident light is refracted in the alignment direction of the liquid crystal molecules by optical anisotropy to thereby display image information.
A liquid crystal display device includes a color filter substrate having a common electrode formed thereon, an array substrate having pixel electrodes formed thereon, and liquid crystal filled between the two substrates. Among liquid crystal display devices, a vertical electric field emission display device which vertically applies an electric field between the common electrode and the pixel electrodes has high transmittance and high aperture ratio, but has poor viewing angle. Many methods were suggested to solve the above-mentioned problems, and one example thereof is a horizontal electric field emission display device. However, a horizontal electric field emission display device shows less change in birefringence depending on a viewing angle direction so that it can have an improved viewing angle characteristic compared to the vertical electric field emission display device.
Recently, a liquid crystal display device that implements a viewing angle control method has been suggested in order for a user to selectively drive a wide viewing angle mode and a narrow viewing angle mode when working on a document which is important for security reasons. However, a conventional liquid crystal display device has a thick insulating layer region formed thereon due to structural and manufacturing process reasons and a deviation in the critical dimension (CD) of a pixel functioning to control viewing angle becomes larger to thereby reduce the aperture ratio and restrict the narrow viewing angle characteristic, and thus an improvement thereof is required.